Incorporating temporal penalties: Note that we are only imposing nonnegativity in \(\mathbf {C}\)  here; after denoising to obtain \(\hat{\mathbf {Y}}\) , we have found that this simple nonnegative constraint is sufficient for the datasets examined here. However, it is certainly possible to incorporate temporal penalties or constraints on \(\mathbf {C}\)  (e.g., a TF penalty or a non-negative auto-regressive penalty as in [1]}), either within each iteration or as a final denoising step.
